Optoelectronic devices with all-inorganic colloidal nanostructured films

ABSTRACT

Optoelectronic devices and methods of producing the same are disclosed. Methods may include forming a film from fused all-inorganic colloidal nanostructures, where the nanostructures may include inorganic nanoparticles and functional inorganic ligands, and the fused nanostructures may form an electrical network that is photoconductive. Other methods may provide an optoelectronic device which may include an integrated circuit or large panel thin-film transistor matrix, an array of conductive regions, and an optically sensitive material over at least a portion of the integrated circuit and in electrical communication with at least one conductive region of the array of conductive regions.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/755,186, entitled “OPTOELECTRONIC DEVICES WITH ALL-INORGANICCOLLOIDAL NANOSTRUCTURED FILMS,” filed Jan. 31, 2013, which is claimspriority under 35 U.S.C. §119 to U.S. Provisional Patent ApplicationSer. No. 61/744,953, entitled “OPTOELECTRONIC DEVICES WITH ALL-INORGANICCOLLOIDAL NANOSTRUCTURED FILMS,” filed on Oct. 1, 2012, all of which arehereby incorporated by reference in their entirety.

BACKGROUND

1. Technical Field

The present disclosure relates in general to optical and electronicdevices, and more particularly, to fused films of all-inorganiccolloidal semiconductor nanometer scale materials (“nanostructures”)including semiconductor nanoparticles and functional inorganic ligands,which may be employed in an optoelectronic device.

2. Background Information

Digital imaging of sensed electromagnetic wavelengths is widely used inmedical, military, industrial, and scientific applications. Imagesensors include arrays of pixelated semiconductors and/or active pixelarrays that are optically sensitive to light (or wavelengths ofelectromagnetic radiation) and convert the incident photons toelectrons. These photodetectors are integrated in circuit, and withother electronic circuits to convert optical signals to electronicsignals, to store charge accumulated by the pixels, to transfer thecharge and/or signals from the array, to convert the analog into digitalsignals, and to process digital data to form still or video digitalimages.

Examples of image sensors include devices that use silicon for sensing,read-out electronics, and multiplexing functions. In some image sensors,optically sensitive silicon photodetectors and electronics are formed onthe same single silicon wafer. In other examples, larger area, flatpanel image sensors consist of a large array of pixels as part of anactive matrix where each pixel has a thin-film transistor (TFT) that canbe externally addressed. Existing TFT array architectures can be usedfor larger area image sensing, however, they cannot tolerate the hightemperature deposition techniques for many photodetecting semiconductormaterials.

Deposition techniques for certain compound semiconductor materials arenot compatible with established silicon integrated circuits. In suchsystems a silicon electronic read-out array and wavelength radiationsensitive photodetector arrays are fabricated separately, resulting in acomplex assembly procedure, low yield, poor resolution and highermanufacturing and assembling costs. In addition, traditional manufactureof semiconductor substrates and optically sensitive semiconductor layersare limited to rigid and relatively small area optoelectronic devices.

Prior methods for solution-based nanoparticle films include volumelosses of 30% or higher which may leave voids, holes, cracks and otherdefects in the film that negatively affect optoelectronic performanceand require post-treatment to repair. All-inorganic colloidalnanostructures including semiconducting nanoparticles can be processedin solution and/or included in inks that can be deposited on a suitablesubstrate. This solution-processing compatibility allows post-processingatop other integrated circuits. In addition, the fabrication ofoptically active films using all-inorganic colloidal nanostructure inkscan be achieved at low temperature to accommodate additional devicestructures including existing and new TFT and organic substrate, andintegrated circuit materials.

In conventional methods, long-chain, organic ligands that are linked tonanoparticles are exchanged for shorter organic or volatile organic orinorganic ligands that are vaporized during a subsequent heating(annealing, sintering) step to provide a film consisting mainly ofnanoparticles and being substantially free of ligands. In otherconventional methods, the nanoparticle ligands may be removed by soakingthe deposited layers in a solvent that dissolves and thus dissociatesthe ligands from the nanoparticles. These methods may often result inpoor fused film qualities that are not preferential for use inoptoelectronic devices, because organic ligand materials may not beremoved once the nanoparticle solutions are deposited and organic ligandmaterials act as insulating materials in the fused films.

It would be desirable to improve existing methods for producingoptoelectronic devices with all-inorganic colloidal nanostructures.

SUMMARY

Embodiments of the present disclosure provide methods for manufacturingfused films for optoelectronic devices. The fused film may incorporatean all-inorganic colloidal nanostructured layer. In addition, theall-inorganic colloidal nanostructured layer may include semiconductornanoparticles that may be processed in a solution and formed into inks

Nanocrystals may be synthesized in order to create the ink that may bethermally treated to form the fused film. During nanocrystal synthesis,semiconductor nanoparticles may be produced by known techniques such asbatch or continuous flow wet chemistry processes. Semiconductornanoparticles may include spherical nanometer-scale, crystallinematerials and other shaped nanometer-scale, crystalline particles suchas oblate and oblique spheroids, rods, wires, the like and combinationsthereof. The semiconductor nanoparticles may include metal,semiconductor, oxide, metal-oxides and ferromagnetic compositions.

After nanocrystal synthesis, the semiconductor nanoparticles may besubject to ligand exchange where organic ligands may be substituted withpre-selected, functional inorganic ligands. The exchange and extractionof organic ligands may provide a solution or ink of all-inorganiccolloidal nanostructures (including functional inorganic ligands andinorganic nanoparticles) that is substantially free of the organicmaterials. In some embodiments, the ligand exchange may involveprecipitating the as-synthesized semiconductor nanoparticles from theiroriginal solution, washing, and re-dispersing in a liquid or solventwhich either is or includes the ligands to be substituted onto thesemiconductor nanoparticles and so completely disassociates the originalligands from the outer surfaces of the semiconductor nanoparticles andlinks the functional inorganic ligands to the semiconductornanoparticles.

The functional inorganic ligands may maintain the stability ofsemiconductor nanoparticles in the solution and provide preferredordering and close-packing of the semiconductor nanoparticles, withoutaggregation or agglomeration, via electrostatic forces. Functionalinorganic ligands are inter-particle media, including inorganiccomplexes, ions, and molecules that eliminate insulating organicligands, stabilize the semiconductor nanoparticles in solution,facilitate close-packing between semiconductor nanoparticles, and createall-inorganic colloidal nanostructures that may be processed in solutionto form all-inorganic films.

After formation of the ink including all-inorganic colloidalnanostructures, the ink may be deposited using spin-coating,spray-casting, or inkjet printing techniques on any suitable substrateconducting or insulating, crystalline or amorphous, rigid or flexible.Once deposited on the substrate, the all-inorganic nanostructured inkmay be transformed into a solid, all-inorganic fused film via thermaltreatment. The fused film may function as an optically active layer foroptoelectronic devices based on the fused all-inorganic colloidalnanostructures incorporated into the fused film. The final materialcomposition, size of the imbedded all-inorganic colloidalnanostructures, and the thickness of the fused film may depend on thelight or wavelength region selected for detection.

According to various embodiment, aspects of the present disclosure mayinclude an imaging system, a focal plane array which incorporates afused film formed that may work as an optically sensitive layer formedon an underlying integrated circuit patterned to measure and relayoptical signals, electronic signals, or both, on a pixel-by-pixel basis,where the signal may be indicative of light absorbed in the medium fromwhich the focal plane array is made. The circuit may achievemultiplexing of the values read from individual pixels into row orcolumns of data, carried by electrodes and stored for digital imaging.Subsequent layers, typically processed from the solution phase, which,with appropriate interfacing, sensitize the underlying focal plane arrayto become responsive to the wavelengths absorbed by these new layers.Their resultant electronic signals may be registered and relayed usingthe underlying chip.

The present disclosure may provide a range of solution-processed fusedfilms that may lie atop the underlying chip or active array. In someembodiments, the present disclosure may provide a method of sensitizinga charge-coupled device (CCD), complementary metal-oxide-semiconductor(CMOS) focal plane array, or thin-film transistor (TFT) active pixelarray using all-inorganic fused films.

Furthermore, the disclosure may provide efficient, highly sensitivephoto detectors based on solution-processed all-inorganic colloidalnanostructured fused films. Additionally, highly sensitivephotodetectors based on a combination of two (or more) types ofsolution-processed all-inorganic colloidal nanostructures, eachincluding a distinct semiconductor material, are provided. Multispectraldetection of electromagnetic radiation wavelengths or ranges ofwavelengths may be facilitated by incorporating various sizes ofall-inorganic colloidal nanostructures within a single, continuousoptically active layer within the optoelectronic device, depositingvaried respective all-inorganic colloidal nanostructures per pixeland/or incorporating stacked (e.g., vertical) fused film layers having afused all-inorganic colloidal nanostructures, where each fused filmrepresents an optically active layer in electrical communication with atleast two electrodes.

In some embodiments, the imaging devices may be efficientphotoconductive optical detectors active in the x-ray, ultraviolet,visible, short-wavelength infrared, long-wavelength infrared regions ofthe spectrum, and are based on solution-processed nanocrystallinequantum dots. Some embodiments may have the potential to be used increating multi-spectral, low-cost, large area, and flexible-substrateimaging systems.

In one embodiment, a film comprises fused nanostructures substantiallydevoid of organic material wherein the nanostructures comprise aninorganic nanoparticle fused with a functional inorganic ligand, andwherein charge carriers are mobile between the nanostructures andthroughout the film.

In another embodiment, a device, comprises (a) a film comprising anetwork of fused all-inorganic nanostructures, wherein thenanostructures include an inorganic nanoparticle fused with a functionalinorganic ligand, and wherein electrical communication exists betweenthe nanostructures and throughout the film, and the film hassubstantially no defect states in the regions where the nanostructuresare fused; and (b) first and second electrodes in spaced relation and inelectrical communication with first and second portions of the networkof fused nanostructures.

Additional features and advantages of an embodiment will be set forth inthe description which follows, and in part will be apparent from thedescription. The objectives and other advantages of the invention willbe realized and attained by the structure particularly pointed out inthe exemplary embodiments in the written description and claims hereofas well as the appended drawings.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments are described by way of example with reference to theaccompanying figures which are schematic and not intended to be drawn toscale.

FIG. 1 is a block diagram of fused film manufacturing method, accordingto an embodiment.

FIG. 2 shows fused film having all-inorganic colloidal nanostructures ona substrate, according to an embodiment.

FIG. 3 depicts a fused film with an electrode, according to anembodiment.

DETAILED DESCRIPTION

Reference will now be made in detail to the preferred embodiments,examples of which are illustrated in the accompanying drawings. Theembodiments described above are intended to be exemplary. One skilled inthe art recognizes that numerous alternative components and embodimentsthat may be substituted for the particular examples described herein andstill fall within the scope of the invention.

The present disclosure is described in detail with reference toembodiments illustrated in the drawings, which form a part hereof. Inthe drawings, which are not necessarily to scale or to proportion,similar symbols typically identify similar components, unless contextdictates otherwise. Other embodiments may be used and/or other changesmay be made without departing from the spirit or scope of the presentdisclosure. The illustrative embodiments described in the detaileddescription are not meant to be limiting of the subject matterpresented.

Definitions

As used here, the following terms may have the following definitions:

“Fused film” refers to a layer of all-inorganic colloidal semiconductornanostructures that may be converted into a solid matrix after a thermaltreatment, and which may be optically active.

“Optically active” refers to a substance's ability to convert optical toelectrical light.

“Semiconductor nanoparticles” refers to particles sized between about 1and about 100 nanometers made of semiconducting materials.

The present disclosure relates to optical devices and methods ofproducing devices from films synthesized from all-inorganic colloidalsemiconductor nanostructures. The all-inorganic colloidal semiconductornanostructures may be fused to form nanocrystalline films (“fusedfilms”) that may be optically active and/or photoconductive and may beused in photodiodes, photodetectors, optical sensors, imaging devices,photovoltaic applications, among others. Devices incorporating the fusedfilms may be designed to absorb specific or multiple electromagneticwavelengths based on the design of the all-inorganic colloidalnanostructures having the fused film.

All-Inorganic Nanostructured Lnks Using Inorganic Functional Ligands

FIG. 1 is a block diagram of a fused film manufacturing method 100.

In order to produce the ink for the manufacturing of fused filmsemployed in optoelectronic devices, nanocrystal synthesis 102 may firsttake place. During nanocrystal synthesis 102, semiconductornanoparticles may be produced using known techniques such as batch orcontinuous flow wet chemistry processes. The known synthesis techniquesfor colloidal nanoparticles may include capping semiconductornanoparticle precursors in a stabilizing organic material, or organicligands, which may prevent the agglomeration of the semiconductornanoparticle during and after nanocrystal synthesis 102. These organicligands are long chains radiating from the surface of the nanoparticleand may assist in the suspension and/or solubility of the nanoparticlein solvents.

Semiconductor nanoparticles employed in the present disclosure may bespherical nanometer-scale, crystalline materials, also known assemiconductor nanocrystals or quantum dots. Other shapednanometer-scale, crystalline particles may be employed including oblateand oblique spheroids, rods, wires, and the like. Semiconductornanoparticles may include metal, semiconductor, oxide, metal-oxides andferromagnetic compositions. The nanoparticles may have a diameterranging between about 1 nm and about 1000 nm, with the preferred rangebeing between about 2 nm and about 10 nm. Due to the small size of thecrystals, quantum confinement effects may manifest resulting in size,shape, and compositionally dependent optical and electronic properties,rather than the properties for the same materials in bulk scale.

Semiconductor nanoparticles may have a tunable absorption onset that hasincreasingly large extinction coefficients at shorter wavelengths,multiple observable excitonic peaks in the absorption spectra thatcorrespond to the quantized electron and hole states, and narrowbandtunable band-edge emission spectra. Semiconductor nanoparticles mayabsorb light at wavelengths shorter than the modified absorption onsetand emit at the band edge. For example, using the same materials, thesemiconductor nanoparticles may be manufactured to be opticallysensitive to the ultraviolet, x-ray, visible, and infrared regions ofthe electromagnetic spectrum by manufacturing nanoparticles in differentsizes.

Inorganic semiconductor nanoparticles may include II-VI, III-V, andIV-VI binary semiconductors. Examples of such binary semiconductormaterials may include ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, HgS, HgSe, HgTe(II-VI materials), PbS, PbSe, PbTe (IV-VI materials), AlN, AlP, AlAs,AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, and InSb (III-V materials).In addition, the semiconductor nanoparticles may be ternary, quaternary,and quinary semiconductor nanostructures and combinations and mixturesof the materials thereof.

In some embodiments, the semiconductor nanoparticles may includecore-shell type semiconductors in which the shell is one type ofsemiconductor and the core is another type of semiconductor, metal,oxide, and metal-oxide compounds or core-shell compositions, andmixtures thereof, which may have conductive or semi conductiveproperties or serve to introduce certain defect states.

Additionally, fused film manufacturing method 100 may involve ligandexchange 104, in which substitution of organic ligands with functionalinorganic ligands may be achieved. Typically, functional inorganicligands may be dissolved in a polar solvent, while organic cappedsemiconductor nanoparticles may be dissolved in an immiscible, generallynon-polar, solvent. These two solutions may then be combined and stirredfor about 10 minutes, after which a complete transfer of semiconductornanoparticles from the non-polar solvent to the polar solvent may beobserved. Immiscible solvents may facilitate a rapid and completeexchange of organic ligands with functional inorganic ligands.

Functional inorganic ligands may be soluble functional reagents that arefree from organic functionality, may have a greater affinity to link tothe semiconductor nanoparticles than the organic ligands, and therefore,may displace the organic ligands from organic capped semiconductornanoparticles. Ligand exchange 104 may involve precipitating the organiccapped semiconductor nanoparticles from their original solutioncontaining organic ligands, washing, and re-dispersing in a liquid orsolvent which either is or includes the functional inorganic ligands.These functional inorganic ligands may disassociate the organic ligandsfrom the outer surfaces of the organic capped semiconductornanoparticles and may link the functional inorganic ligands to thesemiconductor nanoparticles. The functional inorganic ligands maymaintain the stability of semiconductor nanoparticles in the solutionand may provide preferred ordering and close-packing of thesemiconductor nanoparticles without aggregation or agglomeration viaelectrostatic forces. Functional inorganic ligands may assist in thesuspension and/or solubility of the semiconductor nanoparticle insolvents or liquids. Once applied, the functional inorganic ligands maynot substantially change the optoelectronic characteristics of thesemiconductor nanoparticles originally synthesized with organic ligands.

Functional inorganic ligands may include materials that are the same asthe coordinated semiconductor nanoparticle or different to design andaffect the electronic, optical, magnetic, or other properties for thefinal fused films. In some embodiments, two or more types ofsemiconductor nanoparticles may be separately manufactured. Eachdifferent type of semiconductor nanoparticle may be subject to theexchange of organic ligands for functional inorganic ligands and theextraction of post-exchanged organic ligands. Subsequently, the twotypes of semiconductor nanoparticles with functional inorganic ligandsmay be mixed in a solution to create a heterogeneous mixture. Aplurality of semiconductor nanoparticle compositions and/or sizes may beincluded in the all-inorganic nanostructured ink. Functional inorganicligands fused with semiconductor nanoparticles may have the beneficialeffect of making nanostructured surfaces more stable to oxidation andphotoxidation and increase material performance and longevity.

Functional inorganic ligands may include suitable elements from groupssuch as polyatomic anions, transition metals, lanthanides, actinides,chalcogenide molecular compounds, Zintl ions, inorganic complexes,metal-free inorganic ligands, and/or a combination including at leastone of the foregoing. In some embodiments, functional inorganic ligandsmay be partially volatilized, where some portion of the functionalinorganic ligand remains as solid state electronic material within thenanostructured ink.

Examples of polar solvents containing functional inorganic ligands mayinclude 1,3-butanediol, acetonitrile, ammonia, benzonitrile, butanol,dimethylacetamide, dimethylamine, dimethylethylenediamine,dimethylformamide, dimethylsulfoxide (DMSO), dioxane, ethanol,ethanolamine, ethylenediamine, ethyleneglycol, formamide (FA), glycerol,methanol, methoxyethanol, methylamine, methylformamide,methylpyrrolidinone, pyridine, tetramethylethylenediamine,triethylamine, trimethylamine, trimethylethylenediamine, water, andmixtures thereof.

Examples of non-polar or organic solvents containing organic ligands mayinclude pentane, pentanes, cyclopentane, hexane, hexanes, cyclohexane,heptane, octane, isooctane, nonane, decane, dodecane, hexadecane,benzene, 2,2,4-trimethylpentane, toluene, petroleum ether, ethylacetate, diisopropyl ether, diethyl ether, carbon tetrachloride, carbondisulfide, and mixtures thereof; provided that organic solvent isimmiscible with polar solvent. Other immiscible solvent systems that areapplicable may include aqueous-fluorous, organic-fluorous, and thoseusing ionic liquids.

The exchange and extraction of the organic ligands in ligand exchange104 may provide a solution or ink of all-inorganic colloidalnanostructures that may be substantially free of organic materials. Insome embodiments, the relative concentration of the organic ligands tothe semiconductor nanoparticle in the solution of the functionalinorganic ligand may be less than about 10%, 5%, 4%, 3%, 2%, 1%, 0.5%and/or 0.1% of the concentration in a solution of the semiconductornanoparticle with the organic ligands.

Organic materials in organic ligands are known to be less stable andmore susceptible to degradation via oxidation and photo-oxidation;therefore, all-inorganic materials may enhance the stability,performance and longevity of the device. In addition, organic materialsmay act as insulating agents that prevent the efficient transport ofcharge carriers between semiconductor nanoparticles, resulting indecreased device efficiencies.

Semiconductor nanoparticles with inorganic functional ligands may differfrom core/shell nanoparticles where one nanoparticle has an outercrystalline layer with a different chemical formula. The crystallinelayer, or shell, generally forms over the entire semiconductornanoparticle but, as used in the present disclosure, core/shellnanoparticles may refer to those nanoparticles where at least onesurface of the semiconductor nanoparticle is coated with a crystallinelayer. While the functional inorganic ligands may form ordered arraysthat may radiate from the surface of a semiconductor nanoparticle, thesearrays may differ from a core/shell crystalline layer, as they are notpermanently bound to the core semiconductor nanoparticle in theall-inorganic nanostructured ink.

After ligand exchange 104, which may form an all-inorganicnanostructured ink, the ink may undergo a deposition 106 over asubstrate or may be deposited as additional layers to all-inorganicfused films. Deposition 106 techniques may include: blading, growingthree-dimensional ordered arrays, spin coating, spray coating, spraypyrolysis, dipping/dip-coating, sputtering, printing, inkjet printing,stamping, the like and combinations thereof.

Following deposition 106, all-inorganic nanostructured ink may betransformed into a solid, all-inorganic fused film via thermal treatment108. Crystalline films from all-inorganic colloidal nanostructures maybe formed by a low temperature thermal treatment 108. In at least oneembodiment, thermal treatment 108 of the colloidal material may includeheating to a temperature less than about 350, 300, 250, 200, 150, 100and/or 80° C. Fused film 200 may maintain approximately the sameoptoelectronic characteristics as the all-inorganic nanostructured inkor solution including the all-inorganic colloidal nanostructures. Thismay require that the fused film substantially maintains the same sizeand shape of the semiconductor nanoparticles that were deposited fromthe all-inorganic nanostructured ink. Excessive thermal treatment 108may create fused films that do not maintain nanostructures and mayresult in fused films that have optoelectronic characteristics moreclosely performing to the respective bulk semiconductor material.Deposition 106 of all-inorganic nanostructured inks and film fusing viathermal treatment 108 to create all-inorganic nanostructured films maybe performed in repetition to achieve desired film characteristics,including multiple layers, for use in optoelectronic devices.

Continuous Inorganic Fused Films from Inks Having All-Inorganic

Nanostructures

FIG. 2 shows fused film 200. Fused film 200 may be enhanced as anoptically active layer for finished optoelectronic devices based onfused all-inorganic colloidal nanostructures 204 integrated into fusedfilm 200. Final material composition, size of imbedded all-inorganiccolloidal nanostructures 204, and thickness of fused film 200 may bedependent on light or wavelength region selected for detection.Thickness of fused film 200 may range between about 50 nm and about 3um, though thinner or thicker fused films 200 may be employed accordingto the desired functionality of the device.

The functional inorganic ligands may effectively bridge thesemiconductor nanoparticles to form an electrical network and facilitateefficient electronic transport between all-inorganic colloidalnanostructures 204 within fused film 200. The fused all-inorganiccolloidal nanostructures 204, and the juncture between them, maygenerally not have defect states, so current will flow readily betweenthem. This aspect of fusing all-inorganic colloidal nanostructures 204,including functional inorganic ligands, may increase the electronictransport properties between all-inorganic colloidal nanostructures 204and throughout fused film 200, providing a carrier mobility which mayrange within about 0.01 cm²/Vs and about 80 cm²/Vs. Fused film 200having all-inorganic colloidal nanostructures 204 may also exhibit arelatively low electrical resistance above about 25 k-Ohm/square.

Nanostructured ligands remaining in the deposited all-inorganicink/solution to form fused film 200 may not be removed, either before oras a function of the fusing steps or thermal treatment. Furthermore,inks including all-inorganic colloidal nanostructures 204 may lose lessthan about 20%, 15%, 10% and/or 5% of their mass upon a thermaltreatment up to about 400° C. and/or 450° C.

Optical Devices With Optically Active Layers Having All-InorganicNanostructured Fused Films

FIG. 3 depicts a fused film structure 300. Optical devices may includesingle image sensor chips having a plurality of pixelated metal oxidesemiconductors each of which may include fused film 200 that may beoptically active and at least two electrodes 302 in electricalcommunication with fused film 200. Size of pixels may range from lessthan about 1 micron square to about 1 micron square.

Other optical devices may be large-area image sensors including activepixel or matrix arrays incorporating thin film transistors (TFTs) whichmay include fused film 200 that is optically active and at least twoelectrodes 302 in electrical communication with fused film 200. Pixelsize may be reduced to about 40 microns square or may be sized toaccommodate the detected wavelength as required.

Current and/or voltage between electrodes 302 may be related to theamount of light absorbed by fused film 200. Photons absorbed by fusedfilm 200 may generate electron-hole pairs and a current and/or voltage.By determining such current and/or voltage for each pixel, the imageacross the chip may be reconstructed via digital multiplexing and otherintegrated circuit components. The responsiveness of the sensor chips todifferent electromagnetic wavelengths may be made tunable by changingthe material systems for the all-inorganic colloidal nanostructures 204inks and/or changing the size of the all-inorganic colloidalnanostructures 204 within fused film 200 to take advantage of thequantum size effects in all-inorganic colloidal nanostructures 204included in the ink.

Fused film 200 may be deposited and created as a monolithic layer(s)over the image sensor chip, integrated circuit, integrated circuitcomponents, and/or TFT active matrices. Fused film 200 may besolution-deposited onto a substrate 202 or pre-fabricated CCD, CMOS, orTFT electronics.

Image sensor chip, integrated circuit, and/or TFT architecture mayinclude one or more semiconducting materials, such as silicon,silicon-on-insulator, silicon-germanium, indium phosphide, indiumgallium arsenide, gallium arsenide, or semiconducting polymers (forflexible substrate and non-planar devices). Optical device substrates202 may also include plastic and glass. In addition, flexible substrate202 devices may include metal foil and organic substrates.

Additional layers may be included in the layers atop the structure,including additional depositions of all-inorganic colloidalnanostructures 204 on fused film 200 to enable multispectral detectionand subsequent layers of at least partially transparent electrodes.Multiple optically active layers may be layered on the image sensorsubstrate 202 to provide greater sensitivity for the respectivewavelengths, improved imaging for multiple wavelengths, decreasedcomplexity in device architectures (e.g., multilayer, monolithicdeposition and without additional color or wavelength filters).Moreover, additional optically active layers may include additionalcontact electrodes per layer.

Contact electrodes 302 may be at least partially transparent and overlayall-inorganic colloidal nanostructures 204 in fused film 200. Electrode302 materials may include aluminum, gold, platinum, silver, magnesium,copper, indium tin oxide (ITO), tin oxide, tungsten oxide, layerstructures and combinations thereof.

Substrates 202 may include one or more electrodes 302, or electrodes 302may be deposited in a later step. Optical devices may also be large-areaimage sensors on plastic or other flexible substrates.

The embodiments described above are intended to be exemplary. Oneskilled in the art recognizes that numerous alternative components andembodiments that may be substituted for the particular examplesdescribed herein and still fall within the scope of the invention.

What is claimed is:
 1. A film comprising a nanostructure comprising aninorganic nanoparticle fused with a functional inorganic ligand.
 2. Thefilm of claim 1, wherein the nanostructure is devoid of organicmaterial.
 3. The film of claim 1, wherein charge carriers are mobilethroughout the film.
 4. The film of claim 1, wherein the nanostructureis fused with a second nanostructure.
 5. The film of claim 4, whereincharge carriers are mobile between the nanostructure and the fusedsecond nanostructure.
 6. The film of claim 4, wherein the fusednanostructures define a conductive electrical network.
 7. The film ofclaim 4, wherein the fused nanostructures include at least onefunctional inorganic ligand selected from a group consisting ofpolyatomic anions, transition metals, lanthanides, actinides,chalcogenide molecular compounds, Zintl ions, inorganic complexes,metal-free inorganic ligands, and/or a combination thereof
 8. The filmof claim 4, wherein fused nanostructures include nanoparticles ofdifferent compositions and fused functional inorganic ligands.
 9. Thefilm of claim 4, wherein fused nanostructures includes nanoparticles ofdifferent sizes and fused functional inorganic ligands.
 10. The film ofclaim 4, wherein the fused nanostructures have a carrier mobility ofbetween about 0.01 and about 80 cm²/Vs.
 11. The film of claim 4, whereinthe fused nanostructures have a substantially linear response toirradiation in at least a portion of the electromagnetic spectrum. 12.The film of claim 1, wherein fused nanostructures have an electricalresistance of at least about 25 k-Ohm/square.
 13. The film of claim 1,wherein the film has an optical response to irradiation in at least oneof the x-ray, ultraviolet, visible, and/or infrared regions of theelectromagnetic spectrum.
 14. The film of claim 1, wherein the film issubstantially inorganic.
 15. The film of claim 1, wherein the inorganicnanoparticles and functional inorganic ligands are colloidal andincluded in an ink or solution that is deposited and fused, and whereinthe film retains the inorganic nanoparticles and functional inorganicligands.
 16. The film of claim 1, wherein the inorganic nanoparticlesmaintain the same size, shape, and opto-electronic properties of theinorganic nanoparticles that were deposited from the all-inorganicnanostructure ink.
 17. The film of claim 1, wherein the inorganicnanoparticles include semiconductor, metal, metal-oxide, oxide and/ormagnetic alloy materials and/or a combination thereof.
 18. The film ofclaim 1, wherein the inorganic nanoparticles comprise at least one ofPbS, InAs, InP, PbSe, CdS, CdSe, InGaAs, (Cd-Hg)Te, ZnSe(PbS),ZnS(CdSe), ZnSe(CdS), PbO(PbS), and PbSO(PbS).
 19. The film of claim 1,wherein the optical response of the film is determined by a size andcomposition of the inorganic nanoparticles in the film.
 20. The film ofclaim 1, wherein the film is disposed on a substrate.
 21. The film ofclaim 20, wherein the substrate is flexible and formed in a non-planarshape.
 22. The film of claim 20, wherein the substrate comprises anintegrated circuit and/or a thin-film transistor array, at least somecomponents of which are in electrical communication with the film. 23.The film of claim 20, wherein the substrate comprises at least one of asemiconducting organic molecule, a semiconducting polymer, ananocrystalline semiconductor, an amorphous semiconductor, or acrystalline semiconductor.